You are ignoring skill gaps as well as physical abilities which are still needed in certain fields.
if Taiwan is to focus on high-tech industries, hiring engineers in their 50s and 60s will not help, since they are out of touch with new tech. You can only keep the existing ones longer (e.g. reitre at 67 and not 60)
I can share from my family’s experience how difficult it is to rejoin the work force in your 40s (after taking break to raise kids), i think to do so in your 50s is even harder.